Change Color of Radio Button
If you want to change the color of the radio button when checked, you can do this but there are limitations.
With the default style (see below) - there is no way to change this as it is rendered by the browser so we do not have control. It will change appearance by what browser you are using (see an example below in Chrome)
To change the color and appearance, go to Content > Checkbox / Radio Filter Options > Checkbox / Radio Style. Here you can change to be a tickbox or a button (see below)
Now to change the color, go to Design > Checkbox / Radio Button Style
It will then look something like this